DURASTAR Stage 1 Alternate Firing Camshaft

The Callies DURASTAR Stage 1 Alternate Firing Camshaft is engineered to address a common failure point in Duramax engines: crankshaft breakage. The OEM firing order, which ends with cylinder 3 and begins with cylinders 1 and 2, creates a 3-1-2 stress sequence on the crankshaft, particularly at the intersection of the second main journal. This camshaft modifies the firing order to begin on cylinder 1 and end on cylinders 7 and 8, thereby eliminating this over-stress on the crankshaft and enhancing durability. Constructed from a carburized and hardened 8620 steel core, this camshaft is machined and heat-treated entirely in-house by Callies. It utilizes the latest Landis CNC technology for grinding and is inspected with ADCOLE and Jenoptik equipment to ensure high accuracy and consistency. The research and development conducted in the Callies Cam Research Lab, including Spintron testing up to 11,000 RPM, guarantees valvetrain durability for abusive applications. This camshaft fits 2001-2023 GM/Duramax engines. It is explicitly stated that this product cannot be shipped or sold to California and is for off-road use only.